1. Chemical formula for water is :
2. Brass gets discolored in air because of the presence of which of the following gases in air ?
(b) Hydrogen sulphide
(c) Carbon dioxide
3. Which of the following metals forms an amalgam with other metals ?
4. Quartz crystals normally used in quartz clocks etc. is chemically :
(a) silicon dioxide
(b) germanium oxide
(c) a mixture of germanium oxide and silicon dioxide
(d) sodium silicate
5. Bromine is a :
(a) black solid
(b) red liquid
(c) colourless gas
(d) highly inflammable gas